Sampling techniques

volunteers are selected by asking for people to take part; e.g. using an advert

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What is an opportunity sample?

Selected by availability and whoever is able to take part. The first people available.

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What is a random sample?

Identifying all members of the target population then using a random selection method to choose participants. Every member of the target population has an equal chance of being chosen.

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What is a systematic sample?

Selected participants using a system; every nth person on a list.

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What is a stratified/quota sample?

Randomly selects a predetermined number of participants from subgroups in proportion to their numbers in the target population. In quota, participants are chosen by opportunity. These methods provide proprtional representation of subgroups.